Presence of bifidobacteria in the rumen of calves fed different rations.

A study was made on the numbers and species of bifidobacteria present in the rumen of calves fed high-roughage and high-concentrate diets. With the roughage ration the bifidobacteria were not detectable in a 10(-3) dilution, whereas with the concentrate ration their number was high, usually in the order of 10(8) to 10(9)/ml of rumen fluid. The species most represented, identified by means of deoxyribonucleic acid-deoxyribonucleic acid hybridization tests, included Bifidobacterium ruminale, Bifidobacterium globosum, and an apparently new species.